Conventionally, a known disposable diaper has a main body portion that extends from a front belly part to a back part via a crotch part and a pair of side portions through which the front part and the rear part of the main body portion folded in half are joined together to cover the side surfaces of the lumber part of a wearer when the disposable diaper is worn.
The disposable diaper expands in its width direction in a state in which the respective side portions protrude from the main body portion to its both sides. Therefore, the respective side portions are folded inward between the front part and the rear part of the main body portion, whereby the disposable diaper is put in a compact form for shipping (for example, Japanese Unexamined Patent Publication No. H9-131364).
A folding device described in Japanese Unexamined Patent Publication No. H9-131364 has two conveying belts that convey a disposable diaper while sandwiching the same from its both front and rear sides and folding means for folding respective side portions inward between the front part and the rear part of a main body portion.
The respective conveying belts are arranged so as to separate from each other toward a downstream side in the conveying direction of each disposable diaper and convey the disposable diaper with its waist opening directed to the downstream side in the conveying direction. In addition, one of the conveying belts conveys the disposable diaper with the front part of the main body portion attached thereto. The other of the conveying belts conveys the disposable diaper with the rear part of the main body portion attached thereto.
Accordingly, the front part and the rear part of the main body portion separate from each other so as to widen the waist opening as the disposable diaper is conveyed by the respective conveying belts. When such a state is established and the folding means comes in contact with the respective side portions of the disposable diaper and the respective side portions and the folding means are displaced relative to each other with the conveyance of the disposable diaper, the respective side portions are folded inward between the front part and the rear part of the main body portion.
However, the folding device described in Japanese Unexamined Patent Publication No. H9-131364 conveys the disposable diaper with the waist opening directed to the downstream side in the conveying direction. Therefore, if the disposable diaper keeps conveying in the conveying direction of the folding device in this state, the edge portion of the waist opening gets stuck on the opening portion of a packaging bag when the folded disposable diaper is packaged (for example, the disposable diaper is put in the packaging bag). As a result, the disposable diaper cannot be efficiently packaged.